Blackburn had been driving his CleanScapes truck along his usual route when he saw a mother jogging with a stroller. The woman turned the stroller sideways, likely assuming she had "parked and locked" it, at the top of a hill before momentarily leaving it to greet a group of women around the corner.

"She was on a hill and almost immediately when she turned the corner the stroller started to turn and roll down the hill," Blackburn toldKOMO News. "So I started honking the horn and speeding up so I could catch up to it before it got to the intersection, because at the bottom of the hill was a busy intersection with stop signs."

Blackburn honked his horn — a FedEx truck, heading into the intersection, stopped — blocked traffic with his truck, then ran toward the stroller.

Blackburn and another woman were able to stop the stroller just after it hit a curb. The little boy inside was giggling.

"He seemed to be having a great time rolling down the hill…he seemed to enjoy it," Blackburn said.

The baby's mother arrived seconds later, "freaked out and shaking," and quickly left again with her baby without saying a word.

Despite being hailed a hero, Blackburn insists he was "just in the right place at the right time."